What happens in cancer?

You have 200 different types of cell in your body, which usually all live, grow and multiply in harmony. For example, you always have just the right number of liver cells and white blood cells because there are many different signals that control how much and how often your cells divide. If any of these signals are faulty or missing, a cell may start to grow and multiply too much - the beginning of cancer. This can happen in almost any type of cell, anywhere in your body.